Choline-containing compounds quantification by 1H NMR spectroscopy using external reference and noise measurements

Abstract

Proton magnetic resonance spectroscopy (1H-MRS) is largely exploited in clinical settings to non-invasively investigate chemical compounds in human tissues. Applications of 1H-MRS in oncology field are connected to the detection of abnormal levels of choline compounds in more active tumours, providing useful information for cancer diagnosis and treatment monitoring. Since benign lesions may also show presence of a choline peak, implementing absolute evaluation will help differentiating benign from malignant tumours. An external reference procedure was described to provide choline quantification in standard unit of measurements. Spectra were acquired on a 1.5 T scanner using both phantoms and healthy volunteers with a PRESS sequence. The implemented quantification procedure used metabolite and noise measurements on the spectrum to remove large part of scanner settings contributing to metabolites of interest. A standard quantification was also used to compare performances of the noise-based method. In vitro quantification had accuracy and precision in the range (95–99)% and (5–13)%, respectively. When applied to in vivo studies on healthy volunteers, the method provided very close values of choline concentration, more exactly (1.73 ± 0.24) mmol/l. The method proposed can quantify the proper choline content in phantoms as well as in human structures, as brain. The method is ease of use, computational costless and it can be rapidly calibrated and implemented in any centre.